MECHANISM OF MINERAL ADMIXTURE SUPPRESSING ALKALI-SILICA REACTION .2.RETARDATION OF THE TRANSPORT OF NA, K AND OH IONS IN PORE STRUCTURE CAUSED BY ACIDIC ACTION OF MINERAL ADMIXTURE PARTICLES IN MATRIX

Electrical resistance of mortar containing fly ash and granulated blas t furnace slag was much higher than that of pure cement mortar, which showed again that slag and fly ash retarded ion transport toward the r eactive aggregate. This retarding action was activated by the OH ion a nd was a kind of chemical effect. Therefore, the higher the acidity of the mineral admixture, the stronger the retarding action, or the high er the acidity of the binder, the lower the expansion of mortar. We ma y design cementitious materials systems for prohibiting the alkali-sil ica reaction according to its acidity and check it by testing its resi stance.